KALCHEV, R., I. BOTEV, M. HRISTOZOVA, W. NAIDENOW†, G. RAIKOVA-PETROVA, M. STOYNEVA, D. TEMNISKOVA-TOPALOVA, and T. TRICHKOVA. “Ecological Relations and Temporal Changes in the Pelagial of the High Mountain Lakes in the Rila Mountains (Bulgaria)”. Journal of Limnology, vol. 63, no. 1, Feb. 2004, pp. 90-100, doi:10.4081/jlimnol.2004.90.